A jeweler has 3 rings, each weighing 15 g, made of an alloy of 12% silver and 88% gold. He decides to melt down the rings and add enough silver to reduce the gold content to 83%. How much silver should he add?
_________g silver

We have 45 g containing 12% silver, total silver = 5.4 gm, Gold = 39.6 gm

Lets say we add x gm of silver

Now Total silver = 5.4 + x, Total Gold = 39.6, Total weight = 45 +x

83% of (45 +x) = 39.6

83(45+x)/100 = 39.6, 84(45+x) = 3960, 45 +x = 3960/84 = 47.14, x = 2.14

Hence : Answer is 2.14 gm